Transcript XML Web Services Practical Implementations

XML Web Services
Practical Implementations
Bob Steemson
Product Architect
iSOFT plc
www.isoftplc.com
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Introduction
 i.Express Systems Integration (ESI)
 i.Express CHI Interface
 National Programme for Information Technology
 Questions
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i.Express Systems Integration
 Modern external interface to i.Express
 Based on XML and Web Services
 Builds on existing i.Express business objects and
Systems Integration Toolkit (SIT)
 Allow services to be added incrementally
 Flexible configuration (based on XML)
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Support for Trigger Messages
 “Pull” service available now
 “Push” service under development (v12)
 Two possible data formats
– Current data at the time of requesting
– Before and after images of data at the time of event
– Both utilise same code as related enquiry services
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Express Systems
Integration Architecture
Web Server(IIS)
Browser
(IE5.5)
Party
Application
ASP
Pages
3rd
SOAP
ESI
Frame
work
VB
Objects
Request
Request
Handlers
Request
Handlers
Handlers
Log
Handler
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Database
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Trigger Log
ESI Architecture
 ESI Framework
– Single Entry Point passing credentials, target account,
interface name and request type
– Input and output data transmitted as XML
– Security, Validation, Transformations, Lookups, Exceptions
– Dynamically Configured using XML Files
 Request Handlers
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Called from framework using exposed interfaces
Tightly coupled to Express Business Objects
Handlers can call other services internally
New services added as required
Special handler for trigger log messages
 ESI Unit Test Suite
– Tests all ESI services with a single report produced
– Tests configured using XML files
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Schemas
 Services use proprietary (iSOFT) schemas
– Aligns services to the Express data set
– Avoids issues with reference files and coded fields
 Similar to NHSiS Schemas
– Can use XSLT to match NHSiS schemas exactly
 Many services are already available
 Further services are being developed as required
– i.Express v12 will integrate iSOFT Clinical Manager
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Tools Used
 Developed using Visual Basic 6
– MSXML v4 (Validating Parser, DOM, XSLT)
– MS SOAP Toolkit v2 (ISAPI, WSDL, test clients)
 ESI Web Services
– Configuration held as XML documents
 Interactive Test Program
– Load a request document from disk
– Edit request document if necessary
– Call service and display response
 Integrated Test suite
– Tests defined as XML documents
– Tests may be constructed from sub-tests
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What would I change?
 Pass request and response documents as DOM
elements rather than strings
 Further separate security credentials from other
parameters
 Develop a GUI configuration utility
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i.Express CHI Interface
 Web Service client to access external Web Service
 Web Service proxy accessed from ASP pages
 Maintains configuration and logon state
information on host database
 Automatically logs on as required
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i.Express CHI Interface
Architecture
ASP
Page
Creates
Configuration
“Factory”
Reads
Writes
Request
Message
CHI Proxy
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Response
Message
SOAP Toolkit
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Configuration
& State
Information
Configuration
Objects
NHS
Net
CHI Service
Tools Used
 Developed using Visual Basic 6 and ASP
– MSXML v4 (Validating Parser, DOM, XSLT)
– MS SOAP Toolkit v3 (SOAP client)
 Uses XSLT to convert from and to external XML
– Simplifies serialisation and deserialisation
 Simple Emulator for test purposes
– Written using VB6 and MS SOAP Toolkit
– .NET wrapper to solve namespace issues
 Database components written in Data/Basic
 Configuration using ASP pages
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What would I change?
 Should have tested over HTTPS in-house
– Everything worked, except that the server certificate
was loaded in the wrong store
– Difficult to diagnose on-site
 Emulator was a bit too simple
– Namespaces issue was only apparent late in
development
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National Program for IT Requirements
 Interfaces to existing laboratory application
 Connect to integration hub using web services
 Supports HL7 v3 (XML) messaging
 Applications use “flat file” interface
 Needed yesterday!
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National Programme for IT - Solution
 .NET Web service to accept request from hub with
HL7 message and write details as flat file
 .NET NT service to monitor for flat file, convert
data to HL7 results message and pass to hub web
service
 Make use of .NET XML Support where possible
– Automatic creation of classes from XSD Schema
– Object serialisation and de-serialisation using
XmlSerializer class
– Builds on ideas developed for CHI Interface
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Laboratory System
Wrappers
Flat
File
Order
XML
Order
.NET Web
Service
Writes
Order
File
Laboratory
System
Integration
Hub
XML
Results
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Flat
File
Order
Flat
File
Results
.NET NT
Service
Reads
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Results
File
Flat
File
Results
Development – Order Message
 Start with HL7 v3 message specified by NHS IA
 Create XSL to extract relevant data into a flatter
XML document with no namespaces
 Create an XSD schema to describe XSL output
 XSD.EXE creates C# message classes from the XSD
 Write additional C# code:
– Apply XSLT to input document
– Use XmlSerializer to read transformed XML into
message
– Extract data from message objects and write to flat
file
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Development – Results Message
 Create XSD schema for flatter XML document with
results data
 Create XSL to transform this into HL7 v3 format
specified by NHS IA
 XSD.EXE creates C# message classes from the XSD
 Write C# code
– Read data and initialise message objects
– Use XmlSerializer to serialise these as XML
– Apply XSLT to generate HL7 v3 output
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Tools Used
 Visual Studio .NET 2003
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C# programming language - could have used VB.NET
Standard web service support
Standard web services client
XSD.EXE to generate message classes
Standard XML support classes including XmlSerializer
 XSLT Used to transform to and from HL7 v3
– Internal “flatter” XML that can be automatically
serialised and deserialised
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Summary
 Three different implementations of web services
 Show both server and client ends
 Both VB6 and .NET (C#) development
 ESI – designed for future extensibility
 CHI Interface – limited scope to handle small
number of request types
 NPfIT – rapid development requirements
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Questions
 Contact Details
[email protected]
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